Suppression volley fire, from small arms, was a very important aspect of modern warfare, from WWI up until the Korean war. It then became a bit less important to military strategists, as controlling the air space first, was the goal, and with close air support, suppression, or as others would call it, "harassment" volleys from small arms, fell out of the tactics playbook for ground forces.
Own the sky, first, and than just call in an air strike.
In a post nuke world, suppression becomes much more important again.
The lowly 22 long, has an advantage, since you can carry 1000 rounds easily,... till one runs out of 22 long. But you have 50,000 rounds and the perps have far fewer, more precious ammo.